Resolution of third‐degree atrioventricular block after antibiotic therapy in a dog (Canis lupus familiaris) with urinary tract infection

Abstract A 15‐year‐old, spayed, female Boxer dog presented to an emergency facility for collapsing episodes. Third‐degree atrioventricular block that was non‐responsive to atropine was diagnosed on electrocardiography. Initial diagnostics revealed a concurrent urinary tract infection and renal azotaemia. The patient was treated with intravenous antibiotics in hospital, with a temporary transvenous pacemaker in place to provide chronotropic support. During hospitalisation, the patient's rhythm converted to normal sinus rhythm, and permanent pacemaker implantation was not pursued. Follow‐up 11 days after discharge revealed resolution of the urinary tract infection and azotaemia and persistence of normal sinus rhythm. Holter evaluation at 1 month revealed normal sinus rhythm with few intermittent ventricular premature complexes. This report discusses possible causes of reversible third‐degree atrioventricular block and highlights other disease processes to consider when evaluating patients with atrioventricular block.